1. Field of the Invention
The present invention relates to an improved adjustable tilt bracket for attachment to a concrete leveling or finishing tool such as a bull float or fresno which allows a user to adjust the angle of the tool's smoothing plate as it is being pulled towards or pushed away from the user.
2. Description of the Prior Art
It has been well known in the art that many problems and difficulties are encountered in providing a simple and easy means for establishing a level and smooth finish to large slabs of concrete. It is desired that the fine particles of sand and concrete be brought to the surface and that the larger particles, e.g., rocks and/or gravel, distribute themselves through the lower regions of the concrete. This segregation of particles is facilitated by the use of a leveling tool such as a trowel (for small slabs) or a bull float (for large slabs), which the user drags back and forth over the surface of the slab. Once the slab is leveled with the desired particle distribution and the cement is partially set up it is generally necessary to provide a smooth finish. This is accomplished with a trowel (for small slabs) and a fresno (for large slabs).
Bull floats generally comprise a flat smoothing plate of considerable width, e.g., 48" or more and a shorter depth, e.g., 12" with one or more (generally two) rectangular reinforcing ribs running the width of the smoothing plate. Fresnos, which are smaller than bull floats, e.g., 36" to 48" in width and 4" to 8" in depth, are formed of a relatively thin spring steel smoothing plate or blade with a centrally located relatively narrow rectangular reinforcing rib running the width of the plate. Bull floats, as well as fresnos, are adapted to receive handle flanges via bolts threaded into tapped bores in the reinforcing ribs. Long handles can be pivotally attached to the handle flanges.
Long handles attached to handle flanges enable a user, such as a cement mason, to trowel large surface areas. However, a problem arises when using a bull float (or fresno) with a long handle attached thereto. The leading edge of the smoothing plate needs to be slanted upwardly (in the direction of motion) so that the trailing edge will spread the concrete (in the direction of motion) and smooth its surface. Since the float is drawn towards the user and then pushed away, it is necessary to change the angle of incidence by either lowering the long handle when pushing the bull float (or fresno) and raising it when pulling the float. This works adequately when a medium length handle (e.g., less than about ten to twelve feet) is used. If, however, a long handle (e.g., 15 or more feet) is employed the height required to lift the free end of the handle to provide an appropriate angle for the float when pulling it will, in many instances, be out of reach of the user or in the range where he or she can no longer exert adequate force to pull the float. Furthermore, when pushing the float away from the user, to correct the tilt of the edge of the bull float, the handle may have to be lower than the surface of the concrete being prepared.
The problem of changing the angle of a bull float's smoothing plate without requiring any vertical movement of the handle is addressed by U.S. Pat. No. 4,520,527 ("'527 patent") issued to inventors Richard Maggio et al. The '527 patent describes a bull float bracket which changes the angle of the smoothing plate (i.e., bottom surface of the float) in response to a rotation of the handle, independently of the handle height. A yoke is pivotally mounted on a T-shaped strut formed integrally with the smoothing plate. A locking ring, located on each side of the yoke, is secured to a short tubular handle receiving member, adapted to receive the long handle, to accommodate longitudinal forces thereby locking the tubular member and handle to the bull float.
A connecting rod is pivotally mounted at one end to a circumferential point on the forward locking ring and at the other end to the base of the strut. A prior art modification of the '527 bracket utilized a slotted yoke with a bolt threaded into the tubular member so that the bolt slides between the ends of the slot (spaced at about 180.degree.) The force required to rotate the handle receiving member (and the handle) was controlled by the adjustment of a screw (generally a set screw) mounted within a threaded bore in the yoke so that the end of the screw would bear against the outer surface of the tubular handle receiving member. The friction between the end of the set screw and the tubular handle receiving member provide a retarding torque to rotation of the handle, to maintain the angle of incidence of the bracket (and the smoothing plate) after the user had rotated the handle to the desired degree during a subsequent push or pull operation. However, very small changes in the rotation of the set screw would at times result in large changes in the frictional force thereby either allowing the handle to rotate too freely or requiring an excessive force to make subsequent angle changes. This problem was exacerbated as the handle length increased.
The '527 patent illustrates how the bracket was connected to a bull float having a single reinforcing rib in the form of a relatively deep plate. Such brackets have also been connected to bull floats with two spaced reinforcing ribs with the bracket base resting on top of the ribs. However, such brackets have not found use with fresnos because the narrow ribs do not afford a sufficient supporting surface.
The present invention overcomes the above as well as other shortcomings of the prior art devices.